Manganese doping to boost the capacitance performance of hierarchical Co9S8@Co(OH)2 nanosheet arrays

Transition metal sulfides (TMSs) have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity. Herein, we report a self-supported hierarchical Mn doped Co9S8@Co(OH)2 nanosheet arrays on nickel foam (NF) substrate by a one-step metal-organic-framework (MOF) engaged approach and a subsequent sulfurization process. Experimental results reveal that the introduction of manganese endows improved electric conductivity, enlarged electrochemical specific surface area, adjusted electronic structure of Co9S8@Co(OH)2 and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes. The optimal Mn doped Co9S8@Co(OH)2 electrode exhibits an ultrahigh specific capacitance of 3745 F g-1 at 1 A g-1 (5.618 F cm-2 at 1.5 mA cm-2) and sustains 1710 F g-1at 30 A g-1 (2.565 F cm-2 at 45 mA cm-2), surpassing most reported values on TMSs. Moreover, a battery-type asymmetric supercapacitor (ASC) device is constructed, which delivers high energy density of 50.2 Wh kg-1 at power density of 800 W kg-1, and outstanding long-term cycling stability (94% capacitance retention after 8000 cycles). The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices. (c) 2021 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

A novel manganese-doped transition metal sulfide electrode material with excellent electrochemical performance has been successfully prepared, exhibiting high specific capacitance and long cycle life to deliver a high energy density. The study results offer an effective strategy to optimize the application of transition metal sulfides in energy storage devices.